Looper-actuating and retracting mechanism for sewing machines



April 22, 1941. A. B. CLAYTON. 2,239,591

LOOPER-ACTUATING AND RETRACTING uacrmnsu FOR SEWING MACHINES Filed Feb. 20. 1940 2 Sheets-Shet 1 v c d ew ,5. Claytow Wmwe:

April 1941- A. a. CLAYTON 2,239,591

LOOPER-ACTUATING AND RETRACTING MECHANISM FOR SEWING MACHINES Filed Feb. 20, l940 2 Sheets-Sheet 2 tflndl'ew Clazyton Patented Apr. 22, 1941 LOOPER-ACTUATING AND RETRACTING MECHANISM FOR SEWING MACHINES Andrew B. Clayton, Union, N. J., assignor to The Singer Manufacturing Company,

Elizabeth,

N. J a corporation of New Jersey Application February 20, 1940, Serial No. 319,827

Claims.

This invention relates to looper-mechanisms for chain-stitch sewing machines and has as an object to provide an improved and simplified looper-mechanism which has a minimum of connections; in which the actuating elements are relatively short, light and compact; which is devoid of all harsh motions and which therefore is better adapted for high-speed operation than are prior constructions.

Another object of the invention is to provide an improved and simplified means for disconnecting the looper-carrier from its actuating mechanism so that the looper may be retracted from its normal operating position to facilitate threading of the looper, and for positively locking the looper-carrier in its operative position when it has been returned thereto.

With the above and other objects in view, as will hereinafter appear, the invention comprises the devices, combinations and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention, from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

In the accompanying drawings,

Fig. 1 is a front elevation of a two-thread chain-stitch sewing machine embodying the present invention, the cloth-plate, presser-foot, and portions of the feeding mechanism being omitted.

Fig. 2 is a plan view of the lower left end portion of Fig. 1, showing, more particularly the improved looper-mechanism.

Fig. 3 is a vertical sectional view substantially on the line 3-3 of Fig. 2.

Fig. 4 is a vertical sectional view substantially on the line 44 of Fig. 2 showing, in full lines, the looper and its carrier in their operative positions and in dotted lines in their retracted positions to facilitate threading of the loopen Fig. 5 is a detail longitudinal sectional view substantially on the line 5-5 of Fig. 2 showing means, later to be described, for locking the looper-carrier in its operative position.

Fig. 6 is a fragmentary sectional view showing the looper-carrier locking means withdrawn and the looper-carrier swung to inoperative position.

Referring more specifically to the drawings, the invention is disclosed as embodied in a sewing machine having a frame comprising a base I, standard 2, bracket-arm 3 and bracket-arm head 4. Within the head 4 is reciprocably jour naled a needle-bar 5 carrying, at its lower end, an eye-pointed needle 6 which forms one element of a conventional stitch-forming mechanism. The needle-bar is reciprocated in its bearings by the swinging movements of a needlebar actuating lever I fulcrumed at 8 in the arm 3 and actuated by a pitman 9 connected to a crank Ill on a main-shaft driven from a beltwheel II.

For convenience in manufacture and assembly, the main-shaft is preferably made in two sections, of which one, designated as I2, is journaled in bearings I3 at the base of the standard, and the other, designated as I4, is journaled in bearings I5 and I6 formed in bearing-blocks I5 and I6 supported by the base I. The shaftsections I2 and I4 are connected together by a coupling member I! carrying set-screws I8 and I9 engaging, respectively, the adjacent ends of the shaft-sections I2 and I4.

Intermediate the bearings I5 and I6 the shaftsection I4 carries a looper-actuating crank 20, a feed-lift eccentric 2 I, and counterweights 22 and 23. These elements are of greater diameter than the diameter of the bearings I5 and I6 for the shaft-section I4. Therefore, so that the shaftsection may be inserted into its bearings, the bearing-block I6 is made separate from the base I and is removably secured thereto by a screw 24, as shown in Fig. 1. Outside of the bearinghlock I6 the shaft-section I4 has secured thereto, as by set-screws 25, a collar 26 which carries an adjustable feed-drive eccentric 21. A conventional four-motioned work-feeding mechanism designated generally as f is actuated from the feed-lift and feed-drive eccentrics 2I and 21, respectively.

Secured upon brackets 28 and 29, which are formed integral with and project upwardly from the base I, is a throat-plate 30 which supports the work adjacent the stitching point and beneath which is operated the looper, later to be described.

Cooperating with the needle 6 is a chainstitch looper 3| formed with a thread-eye 32 adapted to carry a looper-thread which, during operation of the machine, is concatenated with the needle-thread to form two-thread chainstitches. The looper is given endwise movements, transversely of the shaft I4, and sidewise movements substantially parallel to the axis of the shaft I4 to cause proper concatenation of the needle and looper-threads, all as is common to two-thread chain-stitch sewing machines. The lcoper 3| has its shank-3| fixed in a loopercarrier 33, pivoted upon a shoulder-screw 34 carried by an arm 35 which projects rearwardly from a split collar 36 secured by clamp-screws 36 upon a looper-actuating shaft 37. This looper-shaft is journaled for oscillation and translation in bearings 38 and 39 provided by the base I.

Oscillatory motion is transmitted to the looper-shaft and to the looper carried thereby, from the crank 26 formed on the main-shaft section l4. This crank is surrounded by a two-part strap 41 (see Fig. 3) having upstanding ears 42 to which is pivotally connected, by a pivot-bolt 43, the upper ends 44 of a pitman 45. The lower end of the pitman is connected by a ball-andsocket joint 45 with the free end of an arm 41 having a hub 48 secured on the looper-shaft 3"! by set-screws 49.

Reciprocatory motion is transmitted to the looper-shaft 3'5, thereby to give to the looper its sidewise movements, in timed relation with its endwise movements, by an eccentric 56 carried by a collar secured upon the shaft-section I4. A pitman 52 has, at one end, a strap 52 which surrounds the eccentric 56 and is connected, at its opposite end, by a ball and socket joint 52' with one end of a rock-arm 53, the opposite end of which is clamped upon the upper end of a stub-shaft 54 journaled in an inclined bearing 55 supported by the base I. At its lower end the shaft 54 carries an arm 56 having, at its free end, a ball 51 fitted between the two halves of a split block 58 which, in turn, is fitted between fianges 59 and 60 secured upon the looper-shaft 31. The

arm 53, shaft 54 and arm 56 form, in effect, a

bell-crank lever for connecting the pitman 52 with the looper-shaft 31. The flange 59 forms a part of the hub 48 of the looper-oscillating arm 41, hereinbefore mentioned, while the flange 66 is carried by a collar 6| secured upon the loopershaft 31 by set-screws 62. Thus rotation of the eccentric 50 will, through the elements 52, 53, 54, 56, 51, 58, 59, 60 and 3'! transmit sidewise motion to the looper-carrier and the looper 3! carried thereby.

It will be observed that the means for giving sidewise movements to the looper is exceedingly compact and simple in construction having minimum of joints in which lost motion may develop. Also due to the inclined arrangement of the shaft 54, the arm 56 is relatively short and therefore may be made rigid without being unduly heavy. Likewise this construction affords convenient means for permitting lateral adjustment of the looper-carrier and the looper carried thereby without affecting the looper-actuating mechanism, such adjustment being effected merely by releasing the set-screws 49 and 62, shifting the looper-shaft axially, and then retightening the set-screws.

In its normal operating position the looper 3|, with its thread-eye 32, is located directly beneath the throat-plate 36. In this position the looper-thread may be passed through the threadeye 32, to thread the looper, only with great difficulty. To facilitate threading of the looper, this invention provides .a simplified means for retracting the looper from its operative position so that the thread-eye 32 will be removed from beneath the throat-plate 36 as shown in dotted lines in Fig. 4. To that end, the looper-carrier 33 is formed with an arcuate slot 53 (Fig. 4) through which the looper-shaft 31 extends. When in its operative position the looper-carrier is in the position shown in full lines in Fig. 4,

with the lower end wall 63 of the slot 63 in contact with the shaft 3'! (see also Fig. 5). The looper-carrier is maintained in that position by the contact of the rounded end 64 of an adjustable screw 64, threaded into the looper-carrier 33 and projecting through a radial aperture 31 in the looper-shaft, with the conical end 65= of a spring-pressed plunger 65 slidingly fitted within a bore 3'! formed in the looper-shaft 31. This construction definitely locates and positively holds the looper in its operative position. The screw 64 may be secured in its adjusted position by a jam nut 64'. The plunger 65 is normally held in the position shown in Fig. 5 by a coil-spring 66 surrounding a reduced portion 65 of the plunger 65 and interposed between the head of the plunger and a plug 61 threaded into the end of the looper-shaft. At its outer end the plunger 65 has secured thereto a nut 68 which may serve as a hand-grasp to permit withdrawal of the plunger in opposition to the spring 66.

When it is desired to retract the looper to the dotted line position shown in Fig. 4 for the purpose of threading the looper, the operator grasps the nut 68 and pulls it outwardly thereby withdrawing the conical end 65 of the plunger 65 from beneath the end of the screw 64. Then by grasping the looper or its carrier or some part attached thereto, for example, the looper threadguide 69, the operator tips the looper-carrier forwardly until the upper end wall 63 of the arcuate slot 63 engages the looper-shaft 31 as shown in Fig. 6. The hand-grasp 68 may then be released and the end of the plunger 65 will thereafter abut against the side of the screw until the looper-carrier is returned to its operative position when the plunger will be shifted forwardly by the spring 66 to lock the looper-carrier as shown in Fig. 5.

From the foregoing it will be perceived that this invention has provided an improved and simplified looper-actuating mechanism including a novel and convenient means of retracting the looper to facilitate threading thereof.

Having thus set forth the nature of the invention what I claim herein is:

1. A looper-actuating mechanism for a sewing machine having a base, comprising a rotary mainshaft, 2. looper-shaft rotatably and translatably journaled substantially parallel to said mainshaft at one side of a vertical plane passing longitudinally through the axis of said main-shaft; a looper carried by said looper-shaft; a. crank on said main-shaft; means, including a universal joint, connecting said crank with said loopershaft to transmit oscillatory motions thereto from rotary motions of said main-shaft; an eccentric on said main-shaft; a stub-shaft journaled in said base at the opposite side of said vertical plane with its axis inclined away from said mainshaft; an arm secured to said stub-shaft and extending substantially lengthwise of said mainshaft; a pitman connecting said eccentric with the free end of said arm to transmit oscillatory motions to said stub-shaft; and a second arm connecting the other end of said stub-shaft with said looper-shaft thereby to transmit axial motions thereto from the oscillatory motions of said stub-shaft.

2. A looper-actuating mechanism for a sewing machine having a base, comprising a rotary mainshaft; a looper-shaft rotatably and translatably journaled. substantially parallel to said mainshaft at one side of a vertical plane passing longitudinally through the axis of said main-shaft;

a looper carried by said looper-shaft; a crank on said main-shaft; means, including a universal joint, connecting said crank with said loopershaft to transmit oscillatorymotions thereto from rotary motions of said main-shaft; an eccentric on said main-shaft; a bell-crank lever fulcrumed on said base at the opposite side of said vertical plane with its axis inclined away from said mainshaft; and a pitman connecting said eccentric with one arm of said bell-crank lever to transmit oscillatory motions thereto, the other arm of said bell-crank lever extending upwardly and forwardly beneath said main-shaft and being connected with said looper-shaft thereby to transmit axial motions thereto from the rotary motions of said main-shaft.

3. A looper-actuating mechanism for a sewing machine having a base, comprising a rotary mainshaft; a looper-shaft rotatably and translatably journaled substantially parallel to said mainshaft at one side of a vertical plane passing longitudinally through the axis of said main-shaft; a looper carried by said looper-shaft; a crank on said main-shaft; means, including a universal joint, connecting said crank with said loopershaft to transmit oscillatory motions thereto from rotary motions of said main-shaft; an eccentric on said main-shaft; a bell-crank lever fulcrumed on said base at the opposite side of said vertical plane with its axis inclined relative to said plane; spaced flanges carried by said looper-shaft; a pitman connecting said eccentric with one arm of said bell-crank lever to transmit oscillatory motions to the lever from rotary motions of said eccentric, the other arm of said bell-crank lever extending upwardly and forwardly beneath said main-shaft toward the looper-shaft and having a ball on the free end thereof; and a block mounted on said ball and fitted between said spaced flanges on said looper-shaft, said pitman and bell-crank lever thereby transmitting axial motion to the looper-shaft from the rotary motion of said eccentric.

4. A looper-actuating mechanism for sewing machines comprising an oscillatory looper-shaftprovided with an axial bore and a radial aperture; a member secured to said shaft; a loopercarrier pivotally mounted on said member at one side of said shaft; an element carried by said looper-carrier and adapted to be projected through said radial aperture into said bore; and

means within the bore in said looper-shaft and member at one side of said shaft and having an opening surrounding said shaft; an element carcarried by said looper-carrier and adapted to be projected through said radial aperture; 3 spring-pressed plunger within the bore in said looper-shaft and engaging said element to shift said looper-carrier in a predetermined direction; and a stop to limit the movement of said loopercarrier under the influence of said plunger.

7. A looper-actuating mechanism for sewing machines comprising an oscillatory and axially movable looper-shaft provided with an axial bore and a radial aperture; a member secured to said shaft; a looper-carrier pivotally mounted on saidmember at one side of said shaft; an element carried by said looper-carrier and adapted to have one end thereof projected through said radial aperture into said bore; a spring-pressed plunger located within the bore in said looper-shaft and having a tapered head engaging the end of said element to hold said looper-carrier in a predetermined operative position.

8. looper-actuating mechanism for sewing machines comprising an oscillatory and axially movable looper-shaft provided with an axial bore and a radial aperture; an arm seemed to said shaft; a looper-carrier pivotally mounted on said arm at one side of said shaft and having an opemng through which said looper-shaft extends; an adjustable element carried by said looper-carrier and adapted to be projected through said radial aperture; a spring-pressed plunger located within the bore in said loopershaft and having a conical head radially engagmg said element to hold said looper-carrier in a predetermined operative position with one end wall of said opening in contact with said loopershaft; and means to withdraw said plunger out of contact with said element thereby to permit swinging of said looper-carrier about its pivot to retract the looper-carrier from its operative position.

9. A looper-actuating mechanism for sewing machines comprising an oscillatory and axially movable looper-shaft provided with an axial bore and a radial aperture; a member secured to said shaft; a looper-carrier pivotally mounted on said member at one side of said shaft; a looper secured to said looper-carrier; an element carried by said looper-carrier and adapted to be projected through said radial aperture; and a springpressed plunger having one portion within the bore in said looper-shaft and engaging said element to hold said looper-carrier in a predetermined operative position, and another portion projecting out of said shaft; and provided with a hand-grasp by means of which the plunger may be manually retracted out of contact with said element thereby to permit the looper-carrier to be swung about its pivot to an inoperative position to facihtate threading of said looper.

10. A looper-actuating mechanism for sewing machines comprising an oscillating looper-shaft provided with an axial bore; a looper anda looper-carrier supported from said shaft and swingable relative thereto; a member carried by said looper-carrier; an element slidingly mounted in said bore and adapted, in one position to engage said member thereby to hold said loopercarrier in its operative position and prevent swinging movement thereof; and. means to withdraw said element out of engagement with said member thereby to permit said looper-carrier and looper to be swung to an inoperative position to facilitate threading of the looper.

ANDREW B. CLAYTON. 

